EP0886901A1 - Switchgear device - Google Patents
Switchgear deviceInfo
- Publication number
- EP0886901A1 EP0886901A1 EP97907203A EP97907203A EP0886901A1 EP 0886901 A1 EP0886901 A1 EP 0886901A1 EP 97907203 A EP97907203 A EP 97907203A EP 97907203 A EP97907203 A EP 97907203A EP 0886901 A1 EP0886901 A1 EP 0886901A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- isolator
- terminal
- circuit breaker
- stack
- insulator
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02B—BOARDS, SUBSTATIONS OR SWITCHING ARRANGEMENTS FOR THE SUPPLY OR DISTRIBUTION OF ELECTRIC POWER
- H02B13/00—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle
- H02B13/02—Arrangement of switchgear in which switches are enclosed in, or structurally associated with, a casing, e.g. cubicle with metal casing
- H02B13/035—Gas-insulated switchgear
- H02B13/065—Means for detecting or reacting to mechanical or electrical defects
Definitions
- This invention relates to a switchgear device.
- Power lines in a substation of an electrical transmission network typically operate at a potential several hundred kilovolts (kV) above ground potential.
- the lowest voltage on the British electrical transmission network, for example, is about 145kV before it is stepped down for electrical distribution.
- Switchgear for a substation typically includes circuit breakers of the kind having a fixed and a moving contact The moving contact is powered in response to a trip signal.
- Typical voltages handled by such circuit breakers are between 145kV and 300kV. For the higher voltages of around 420kV, a double contact is currently used.
- the conventional circuit breaker is usually housed m a porcelain stack which acts as an insulator.
- a typical voltage transformer for use at high voicage is most commonly of the capacitor divider type.
- a plurality of capacitors is linked in series between the power line, at several hundred kV, and ground. Each capacitor drops a fraction of the total potential difference between these two points, and a voltage proportional to the line voltage is tapped off the capacitor closest to ground.
- capacitor voltage transformers have an isolating electromagnetic voltage transformer in parallel with the capacitor closest to ground. This produces an output in the region of 50VA which is used to drive the protection devices.
- the internal impedance of the CVT (and hence the size of the capacitors) necessary to deliver this power is dictated by the magnitude of this outpu .
- the electromagnetic voltage transformer has a non-uniform frequency response. It tends to store energy, thereby distorting transients. It has been proposed to substitute the electromagnetic voltage transformer with an electronic isolator circuit with a high input impedance. The voltage drop across the capacitor in the stack closest to ground is used as the input to the isolator circuit, which in turn produces an optical output signal proportional to the monitored voltage. The optical output signal is then transmitted across the substation to a complementary circuit which reconstitutes the output voltage and power of the CVT.
- each circuit breaker and each CVT is a labour intensive exercise. Each item has had to be installed separately.
- a switchgear device comprising a housing, first, second and third electrical terminals, a circuit breaker in the housing connected between the first and second terminals, a plurality of serially connected capacitors also in the housing and connected between the second terminal and the third terminal, and an electronic isolator connected across at least one of the capacitors and the third terminal, the isolator being operable to provide an output signal that is indicative of the voltage across the second and third terminals.
- the inventor has appreciated that it is possible to realise significant savings in the cost of constructing an electricity substation if the number of devices that have to be installed can be reduced.
- the electronic isolator has a high input impedance, the series of capacitors is effectively buffered.
- the inventor has realised that it is therefore possible to reduce the size of the plurality of capacitors.
- Substantial advantages arise from employing electronic circuitry rather than an electromagnetic voltage transformer.
- the CVT is now small enough to be located along with a circuit breaker in a standard single-break circuit breaker housing because of the reduction in size of the capacitors. This substantially reduces the number of separate switchgear devices that have to be installed in an electricity substation. Since the installation of the devices themselves is a significantly expensive part of a substation, the financial benefit is substantial.
- the housing contains an insulator and a base, the insulator comprising, for example, first and second stacks of insulator material mounted on the base and separated by the second terminal, the first terminal being mounted on the end of the second stack remote from the base.
- the electronic isolator which may include a microprocessor, is located in the base, and substantially all of the capacitors and the circuit breaker are in the insulator.
- the isolator is connected via a cable to signal conditioning means, the signal conditioning means being outside of the housing.
- the cable may be a coaxial cable or a fibre-optic cable, for example. Fibre-optic cable is particularly attractive as it overcomes the problem of electromagnetic noise which tends to affect coaxial cables.
- the circuit breaker may comprise first and second contacts between the first and second electrical terminals, and a contact actuator mechanism. If tne switchgear device has a base, t is preferable that the drive mechanism is located there.
- FIG. 1 shows a switchgear device according to the present invention including a circuit breaker; and, Figure 2 shows a schematic diagram of an isolator circuit and a complementary circuit for driving protection relays.
- a switchgear device is shown generally at 10.
- the device 10 comprises a base unit 150, a lower insulator 130 situated on the base unit, and an upper insulator 140 on top of the lower insulator, the two insulators being separated by a first, lower terminal 90.
- a second, upper terminal 100 is positioned on top of the upper insulator 140.
- the lower insulator 130 provides mechanical support for the upper insulator 140 as well as insulation for the first terminal 90.
- the insulators are typically constructed as a stack of shedded porcelain collars or other commercially available insulating materials as will be familiar to those skilled in the art. Each stack is filled with sulphur hexaflouride (SF,) which has good insulating and arc quenching properties.
- SF sulphur hexaflouride
- a stack of capacitors 30 is connected in series between the first terminal 90 and a ground terminal.
- Each of the capacitors is of the polypropylene type with a total capacitance for the stack 30 of around 1 nanofarad (nF) .
- An electronic isolator circuit 20 is connected in parallel across the lower capacitor 40 of the stack 30 which is connected to ground.
- a circuit breaker 50 is located cetween the second terminal 100 and the first terminal
- This circuit breaker is of the "single break" type, and comprises a hydraulic actuator mechanism (not shown) within the base unit 150.
- the hydraulic actuator mechanism is attached to a connecting rod 60 located in the lower insulator 130, the end of the rod 60 distal from the hydraulic actuator mechanism being attached to a first breaker contact 70 in the upper insulator 140.
- a second breaker contact 80 is also located in the upper insulator 140, and is attached to the second terminal 100.
- the lower insulator (130) thus conveniently provides mechanical coupling of the first breaker contact 70 to the grounded hydraulic actuator mechanism.
- the isolator circuit 20 is connected to a complementary receiver circuit 120 via a fibre-optic cable 110.
- the arrangement is shown in schematic form in Figure 2.
- the voltage across the lower end capacitor 40 of the capacitor stack 30 of Figure 1 is used as an input to the isolator circuit 20.
- the isolator 20 generates a signal suitable for transmission along the fibre-optic cable 110, using a pulsed laser diode 200. This is preferable as the fibre-optic cable is immune to the substantial electromagnetic interference in an electricity substation.
- the signal generated by the diode 200 is received at the complementary receiver circuit 120 by a detector 210 comprising a photodetector 220 and suitable amplifier circuitry 230 to amplify the low power electrical output signal from the photodiode 200.
- the output from the detector 210 enters a decoder 240 which converts the digital transmission signal protocol used by the isolator circuit 20 and detector 210 into a protocol suitable for use with a protection relay.
- the protection relay or relays may be of the type that require only minimal input Dower, such as is manufactured by A.B.B. Switchgear A.B. cf Sweden.
- the isolator circuit 20 only needs to provide a very low level output.
- the protection relays quickly switch out faulted sections of the power system, thus preventing any slowdown in the localised electricity generator from causing a loss in synchronism with the rest of the power system.
- the electronic circuit 20 has a high input impedance and the capacitor stack 30 is thus buffered.
- the reduced output power requirement relative to the electromagnetic voltage transformer allows the physical size and capacitance of each capacitor in the stack 30 of Figure 1 to be reduced signi icantly for a similar voltage rating. As the capacitor stack 30 occupies the biggest proportion of space within the hollow insulator 130, this reduction in size can be used in the present invention to particular advantage.
- the principle cost of a CVT arises from its insulation.
- the typical electrical substation has 50 circuit breakers currently costing around £50,000 each, and 50 CVT ⁇ costing around £2,000.
- the cost of installing and commissioning a CVT is currently in the region of £2,000.
- the isolator circuit 20 may be connected to the complementary receiver circuit 120 via a less expensive coaxial cable rather than a fibre-optic cable, the former being suitable where electrical noise is not such a significant problem, for example.
- the signal generated by the isolator circuit may be an analogue signal rather than a digital signal, the amplitude of the analogue signal can be much lower than previously possible which avoids the need for a power amplifier.
- the polypropylene-insulated capacitors may be replaced by any suitable capacitance m order to step down the voltage from the first, lower terminal 90.
- the circuit breaker may consist of two or more contact assemblies rather than the one illustrated in Figure l, and may additionally or al t ernatively use a spring or other mechanism rather than a hydraulic mechanism.
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Gas-Insulated Switchgears (AREA)
- Driving Mechanisms And Operating Circuits Of Arc-Extinguishing High-Tension Switches (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
GB9605367 | 1996-03-14 | ||
GBGB9605367.3A GB9605367D0 (en) | 1996-03-14 | 1996-03-14 | Switchgear device |
PCT/GB1997/000702 WO1997034349A1 (en) | 1996-03-14 | 1997-03-13 | Switchgear device |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0886901A1 true EP0886901A1 (en) | 1998-12-30 |
EP0886901B1 EP0886901B1 (en) | 2000-10-25 |
Family
ID=10790379
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP97907203A Expired - Lifetime EP0886901B1 (en) | 1996-03-14 | 1997-03-13 | Switchgear device |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0886901B1 (en) |
CN (1) | CN1213464A (en) |
DE (1) | DE69703384T2 (en) |
GB (1) | GB9605367D0 (en) |
WO (1) | WO1997034349A1 (en) |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2002062023A1 (en) | 2001-01-31 | 2002-08-08 | Teldix Gmbh | Modular and scalable switch and method for the distribution of fast ethernet data frames |
US9105391B2 (en) | 2006-08-28 | 2015-08-11 | Avago Technologies General Ip (Singapore) Pte. Ltd. | High voltage hold-off coil transducer |
US20080278275A1 (en) | 2007-05-10 | 2008-11-13 | Fouquet Julie E | Miniature Transformers Adapted for use in Galvanic Isolators and the Like |
US7852186B2 (en) | 2006-08-28 | 2010-12-14 | Avago Technologies Ecbu Ip (Singapore) Pte. Ltd. | Coil transducer with reduced arcing and improved high voltage breakdown performance characteristics |
US7791900B2 (en) | 2006-08-28 | 2010-09-07 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Galvanic isolator |
US9019057B2 (en) | 2006-08-28 | 2015-04-28 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Galvanic isolators and coil transducers |
CN101447327B (en) * | 2008-09-27 | 2010-12-15 | 国网武汉高压研究院 | Method for improving stain resistance of capacitor voltage transformer and device thereof |
JP5476524B2 (en) * | 2009-09-02 | 2014-04-23 | 株式会社明電舎 | Vacuum capacitor type instrument transformer |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE2325449B2 (en) * | 1973-05-17 | 1978-09-14 | Siemens Ag, 1000 Berlin Und 8000 Muenchen | Voltage converter for a fully insulated high-voltage switchgear |
DE3532524A1 (en) * | 1985-08-23 | 1987-02-26 | Bbc Brown Boveri & Cie | Device for measuring the transient potential of the encapsulation of a metal-encapsulated, gas-insulated high-voltage installation |
FR2649245B1 (en) * | 1989-06-29 | 1994-02-25 | Gec Alsthom Sa | HIGH VOLTAGE CIRCUIT BREAKER WITH BUILT-IN VOLTAGE DETECTION DEVICES |
FR2698696B1 (en) * | 1992-11-27 | 1995-01-06 | Simplex Appareils | Voltage measurement set for electrical distribution network. |
FR2720511B1 (en) * | 1994-05-25 | 1996-07-05 | Gec Alsthom T & D Sa | Method and device for removing a disturbing component from a periodic signal and application to an electronic capacitive voltage transformer. |
-
1996
- 1996-03-14 GB GBGB9605367.3A patent/GB9605367D0/en active Pending
-
1997
- 1997-03-13 DE DE69703384T patent/DE69703384T2/en not_active Expired - Fee Related
- 1997-03-13 CN CN 97193045 patent/CN1213464A/en active Pending
- 1997-03-13 EP EP97907203A patent/EP0886901B1/en not_active Expired - Lifetime
- 1997-03-13 WO PCT/GB1997/000702 patent/WO1997034349A1/en active IP Right Grant
Non-Patent Citations (1)
Title |
---|
See references of WO9734349A1 * |
Also Published As
Publication number | Publication date |
---|---|
DE69703384D1 (en) | 2000-11-30 |
WO1997034349A1 (en) | 1997-09-18 |
DE69703384T2 (en) | 2001-02-22 |
EP0886901B1 (en) | 2000-10-25 |
CN1213464A (en) | 1999-04-07 |
GB9605367D0 (en) | 1996-05-15 |
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